1. Field of the Invention
The present invention concerns an unit for measuring the speed and traveled distance of a moving person or object with a Doppler Radar sensor.
In the modern recreational society, daily exercises and sports are for most people a definite part of life. The sports enthusiast can choose between a wide variety of sports such as jogging, bike racing, mountain biking, riding, skiing and so on. In most of these sports, there are no possibilities for the athlete to calculate and control his performance, specifically, speed and distance. Not only for the amateur, but especially for the professional, it is of great importance to be able to control and measure training expenditure and intensity during exercise. The best known and most accurate sensor to measure speed is the Doppler Radar Sensor which works on the basis of the so-called Doppler-Effect, according to which the frequency distribution between the source of radiation and the reflecting signal is directly proportional to the relative speed between the sensor and the reflecting object. Making use of this, either the sensor or the object, or both can move at the same time. Conventional Doppler Sensors are usually like a hollow resonator and built e.g. into cars or the like. They are usually relatively large, heavy and inconvenient. An object which would allow an athlete to measure and control his speed and distance during exercise does not exist.
2. Discussion of the Prior Art
The object of the present invention is to provide a unit for measuring speed and distance of a moving user or object with a Doppler Radar Sensor to enable the measurement, the control and the testing of the speed and traveled distance in a simple, exact way without hindering free movement.
This object is achieved by a unit in which the Doppler Radar Sensor is attachable to a moving user or object, and consists of a Microwave Strip Transmission Line Sensor which produces signals and guides them to an Evaluation Unit, said unit comprising a transmitter that sends analyzed data to a separate Processing and Display Unit. Here, the analyzed date are preferable sent via radio signals. It is also possible to realize transmission via conductors or wires, or to use the human body or the object as a transfer medium.
With an uneven speed or jerking movement of the user or object, the present invention produces measuring signals with interruptions and mistakes. It is therefore an additional object of the present invention to produce a process by which the unit of the present invention can produce accurate and reliable measuring signals even when the user or object is moving unevenly. This object is achieved by a unit and a process.
The used Microwave Strip Transmission Line Sensor is, for example, a sensor of the type used in the German patent applications DE 39 394 1125 and DE 39 22 165. Sensors of this type operate with high reliability, high accuracy and especially have little weight, are small in size and have acceptable production costs. The signal frequency of the Microwave Strip Transmission Line Sensor used in the present invention is preferably 5.86 Hz. The Microwave Strip Transmission Line Sensor is turned by 20xc2x0 to 60xc2x0 with respect to the ground normal. A part of the emitted radiation gets diffuse when it hits the ground and is then again received by the sensor. The frequency of the received signal is shifted with respect to the sending frequency. The differential frequency xcex94f is proportional to the relative speed v between the moving user or object and the ground, and inversely proportional to the cosine of the angle xcex1 between Microwave Strip Transmission Line Sensor and the ground normal:
xcex94fxcex1/cos xcex1
The Frequency Analysis of the Differential Frequency Signal for calculating the speed information in the Evaluation Unit is advantageously taking place through a Fourier Analysis or simply through a Zero Transition Counter.
Through the physical separation of the Microwave Strip Transmission Line Sensor and the Evaluation Unit from the Processing and Display Unit, a moving user is given the possibility to measure his own speed and traveled distance during movement. It is also possible to measure, control and analyze speed and traveled distance of a moving object, to which the Microwave Strip Transmission Line Sensor and the Evaluation Unit are fixed. This can be accomplished by moving with the object (bike or horse) or by a non-moving user having the Processing and Display Unit.
Since the Microwave Strip Transmission Line Sensor and the Evaluation Unit are attached and carried by a moving user or object, it is advantageous to build them small, light and easy to carry, so that it will not impede and interrupt movement. The separate Processing and Display Unit should preferably also be, small, light and easy to carry, if it is also to be carried by the moving user. Even if the one who carries the separate Processing and Display Unit does not move and wants to measure the speed and traveled distance of a moving object, it is advantageous to build the Processing and Display Unit small, light and easy to carry. This could e.g. be the case if a discus thrower or a javelin thrower (or a similar athlete) wants to measure the speed and traveled distance of his athletic instrument, even when he is not moving.
It is also possible to build the Processing and Display Unit in a stationary way, e.g. attached to a computer. This is advantageous when a trainer wants to control and analyze the performance of his athletes during training, and then immediately use these results in the training session. For these aplications the Processing and Display Unit can have a more extensive software and more user-friendly operating and displaying possibilities than the portable version.
It is advisable to secure the Microwave Strip Transmission Line Sensor and the Evaluation Unit in a casing with an elastic belt, buckle, clip or a similar device on the athlete or his clothing, e.g. on runners, ice skaters, long distance runners or athletes who perform a similar motion. The best place to attach the inventive object for the previously mentioned movements would be the hip, since it experiences the least amount of rocking. The sensor, when attached to the user or object, has to be built into a casing in such a way that the emitted signals will hit the ground at an angle. The separate Processing and Display Unit can be attached to the wrist of a moving user with a wrist band, so that the user can, at all times access and monitor the data.
It is also possible to combine the Microwave Strip Transmission Line Sensor and the Evaluation Unit with an Acceleration Sensor, which can be a semiconductor. This makes it possible to shut off the Microwave Sensor at a consistent speed and activate it only at a change of speed which will then be registered by the Acceleration Sensor thus reducing the power consumption of the present invention considerably.
Furthermore, a Temperature Compensation Pressure Sensor can be integrated for air pressure measurement, i.e. to calculate changes in air pressure or reached altitude. Since a speed signal to be measured through 1/COS xcex1 depends on an angle of inclination a between the radar signals and the reflecting surface, errors through the inclination of the surface can be compensated by the use of an integrated Altitude Meter. This is very important e.g. for a mountain climber or hiker. From the reached altitude and measured speed calculations, this can be used to determined the inclination of the surface and the true speed. With the Pressure Sensor calculations to determine the reached altitude and the speed of ascend and descend can be reported and recorded.
The present invention can also be constructed in a fashion that after completing the physical exercise all the speed values in a specific time frame stored in the Evaluation Unit or the Processing and Display Unit are transferred to a computer via an inductive interface for further analysis.
The present invention can be used for all athletic activities or other activities in which a user or object is moving. Specifically to be listed here are all kinds or running and walking exercises, also cross-country skiing, alpine skiing, ice skating, roller skating and roller blading, biking, bobsledding, all kinds of equestrian sports, surfing, sailing, dog sledding and so on. In the case of e.g. a skier the Microwave Strip Transmission Line Sensor and the Evaluation Unit can be integrated or attached to the ski boot or in the ski boot or the ski itself. With equestrian sports, the sensor and Evaluation Unit can e.g. be attached to a belt around the horses belly or integrated into the saddle. The separate Processing and Display Unit can then be attached to the wrist of the rider.
The present invention favourably also includes:
means for converting the analog signals of the Microwave Strip Transmission Line Sensor (1) into digital signals
means for periodically scanning the digital signal, means for converting each periodically scanned signal segment into a Frequency Spectrum A (f),
means for determining a Frequency Barrier F of the respective current Frequency Spectrum A (f),
means for calculating the current speed or the traveled distance of the moving user or object from the Frequency Barrier F of the respective current Frequency Spectrum A (f).
The means for converting each of the signal segments into a Frequency Spectrum A (f) preferably comprises means for multiplicating a respective signal segment with a Hamming Window and means for a subsequent Fourier Transformation of the multiplied signal segments. The means for determining the Frequency Barrier F of the respective current Frequency Spectrum A (f) preferably comprises:
A) means for determining a Threshold Indicator S, with S less than A(f=0),
B) means for comparing the Threshold Indicator S with the Frequency Spectrum A(f), from the frequency f=0 in the direction of ascending frequencies to a predetermined barrier frequency fG,
C) means for determining a first frequency value f1 at A(f=f1)=S,
D1) means for determining f1 as the required Frequency Barrier F on the condition A(f) smaller than S for f1 less than fxe2x89xa6fG,
D2) means for determining a second frequency value f2 xcex5t A(f=f2)=S on the condition A(f) not smaller than S for f1 less than fxe2x89xa6fG,
E) means for comparing the Threshold Value shortage d=f2xe2x88x92f1 with fixed values y and z, whereby y less than z,
F1) means for ignoring f1 and f2 and means for further comparing A(f) and S corresponding to the steps (C) et seqq. until barrier frequency fG, on the condition d less than y,
F2) means for not noticing or ignoring the actual Frequency Spectrum A(f) on the condition y less than dxe2x89xa6z,
F3) means for determining f1 as the required Frequency Barrier F on the condition d greater than z.
Furthermore, the present invention can include means for a plausibility control of the speed values determined from the respective current Frequency Spectrum A(f), comprising:
means for estimating the acceleration performance of a moving user or object with the relationship:
P=m(v22xe2x88x92v21)/2xcex94t
in which m is the mass of the moving user or object; v1 is the speed of the moving user or object determined from the respective preceding Frequency Spectrum A1(f); v2 is the speed of the moving user or object determined from the current Frequency Spectrum A2(f) and xcex94t is the time which passes between the scanning of both Frequency Spectrums,
means for comparing the determined Acceleration Performance P with a fixed upper and a fixed lower acceleration border (Pmin or Pmax) comprising means for ignoring the speed values v2 on the condition P less than Pmin or P greater than Pmax, and means for determining v2 as the current speed value on the condition Pmin less than P less than Pmax.
The present invention also includes a process for determining the speed or the traveled distance of a moving user or object from the Measurement Signal, which is produced by a Microwave Strip Transmission Line Sensor (1) from one of the inventive devices, in which the process includes the following steps:
1) conversion of the analog Measurement Signal of a Microwave Strip Transmission Line Sensor into a digital Signal,
2) periodic scanning of the Digital Signal,
3) conversion of the periodically scanned signal parts into a respective Frequency Spectrum A(f),
4) determination of a Frequency Barrier F of the respective current Frequency Spectrum A(f),
5) calculation of the current speed or traveled distance of the moving user or object from the Frequency Barriers of the Respective Current Frequency Spectrum A(f).
The conversion of the signal parts into a Frequency Spectrum A(f) is advantageously accomplished by the multiplication of a signal portion with a Hamming Window and a subsequent Fourier Transformation of the multiplied signal parts.
The determination of the Frequency Barrier F of the respective current Frequency Spectrum A(f) can be accomplished by the following steps:
A) determination of a Threshold Indicator S in which S less than A (f=0),
B) comparison of the Threshold Indicator S with the Frequency Spectrum A(f), from the frequency f=0 in the direction of increasing frequency up to a fixed border frequency fG,
C) determination of a first frequency value f1, with A(f=f1)=S,
D1) if A(f) less than S for f1 less than fxe2x89xa6fG: determine f1 as the required Frequency Barrier F, otherwise
D2) determine a second frequency value f2, with A(f=f2)=S whereby f2 greater than f1,
E) compare the Threshold Value shortage d=f2xe2x88x92f1 with fixed values y and z, whereby y less than z,
F1) if d less than y: ignore f1 and f2, additional comparison of A(f) and S corresponding to steps C) et seqq. until border frequency fG,
F2) if y less than dxe2x89xa6z: ignore the current Frequency Spectrum A(f),
F3) if d greater than z: determination of f1 as the required Frequency Barrier F.
Advantageously, a Plausibility Control of the speed value calculated from the respective current Frequency Spectrum A(f) is carried out in the following steps:
Estimation of the Acceleration Performance of the moving user or object with the relationship:
P=m(v22xe2x88x92v21)/2xcex94t
in which m is the mass of the moving user or object; v1 is the calculated speed of the moving user or object from the respective preceding Frequency Spectrum A1(f); v2 is the calculated speed of the moving user or object from the current Frequency Spectrum A2(f); and xcex94t is the time which passed between the scanning of both Frequency Spectrums,
means for comparing the determined Acceleration Performance P with a fixed upper and a fixed lower acceleration border (Pmay or Pmin):
in case P less than Pmin or P greater than Pmay: ignore speed value
in case Pmin less than P less than Pmax: determination of V2 as current speed value.